Enhanced isosteric heat, selectivity, and uptake capacity of CO2adsorption in a metal-organic framework by impregnated metal ions

Abstract

We demonstrate by experimental and theoretical studies that the impregnation of various metal ions such as Li⁺, Mg²⁺, Ca²⁺, Co²⁺, and Ni²⁺ in the pores of an anionic MOF, [Zn₃(TCPT)₂(HCOO)][NH₂(CH₃)₂] (SNU-100′) significantly enhances isosteric heat, selectivity, and uptake capacity of the CO₂ adsorption in the MOF. Due to the electrostatic interactions between CO₂ and the extra-framework metal ions, the isosteric heats of CO₂ adsorption are increased to 37.4–34.5 kJ mol⁻¹ and the adsorption selectivities of CO₂ over N₂ at room temperature are increased to 40.4–31.0, compared with those (29.3 kJ mol⁻¹ and 25.5, respectively) of the parent MOF (SNU-100′) containing [NH₂(CH₃)₂]⁺ cations.